.\"	$OpenBSD: SSL_load_client_CA_file.3,v 1.9 2019/06/12 09:36:30 schwarze Exp $
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.Dd $Mdocdate: June 12 2019 $
.Dt SSL_LOAD_CLIENT_CA_FILE 3
.Os
.Sh NAME
.Nm SSL_load_client_CA_file ,
.Nm SSL_add_file_cert_subjects_to_stack ,
.Nm SSL_add_dir_cert_subjects_to_stack
.Nd load certificate names from files
.Sh SYNOPSIS
.In openssl/ssl.h
.Ft STACK_OF(X509_NAME) *
.Fn SSL_load_client_CA_file "const char *file"
.Ft int
.Fo SSL_add_file_cert_subjects_to_stack
.Fa "STACK_OF(X509_NAME) *stack"
.Fa "const char *file"
.Fc
.Ft int
.Fo SSL_add_dir_cert_subjects_to_stack
.Fa "STACK_OF(X509_NAME) *stack"
.Fa "const char *dir"
.Fc
.Sh DESCRIPTION
.Fn SSL_load_client_CA_file
reads PEM formatted certificates from
.Fa file
and returns a new
.Vt STACK_OF(X509_NAME)
with the subject names found.
While the name suggests the specific usage as a support function for
.Xr SSL_CTX_set_client_CA_list 3 ,
it is not limited to CA certificates.
.Pp
.Fn SSL_add_file_cert_subjects_to_stack
is similar except that the names are added to the existing
.Fa stack .
.Pp
.Fn SSL_add_dir_cert_subjects_to_stack
calls
.Fn SSL_add_file_cert_subjects_to_stack
on every file in the directory
.Fa dir .
.Pp
If a name is already on the stack, all these functions skip it and
do not add it again.
.Sh RETURN VALUES
.Fn SSL_load_client_CA_file
returns a pointer to the new
.Vt STACK_OF(X509_NAME)
or
.Dv NULL on failure .
.Pp
.Fn SSL_add_file_cert_subjects_to_stack
and
.Fn SSL_add_dir_cert_subjects_to_stack
return 1 for success or 0 for failure.
.Pp
All these functions treat empty files and directories as failures.
.Pp
In some cases of failure, the reason can be determined with
.Xr ERR_get_error 3 .
.Sh EXAMPLES
Load names of CAs from a file and use it as a client CA list:
.Bd -literal
SSL_CTX *ctx;
STACK_OF(X509_NAME) *cert_names;
\&...
cert_names = SSL_load_client_CA_file("/path/to/CAfile.pem");
if (cert_names != NULL)
	SSL_CTX_set_client_CA_list(ctx, cert_names);
else
	error_handling();
\&...
.Ed
.Sh SEE ALSO
.Xr PEM_read_bio_X509 3 ,
.Xr ssl 3 ,
.Xr SSL_CTX_set_client_CA_list 3 ,
.Xr X509_get_subject_name 3 ,
.Xr X509_NAME_new 3
.Sh HISTORY
.Fn SSL_load_client_CA_file
first appeared in SSLeay 0.8.0 and has been available since
.Ox 2.4 .
.Pp
.Fn SSL_add_file_cert_subjects_to_stack
and
.Fn SSL_add_dir_cert_subjects_to_stack
first appeared in OpenSSL 0.9.2b and have been available since
.Ox 2.6 .
.Sh AUTHORS
.Fn SSL_add_file_cert_subjects_to_stack
and
.Fn SSL_add_dir_cert_subjects_to_stack
were written by
.An Ben Laurie Aq Mt ben@openssl.org
in 1999.
.Sh BUGS
In some cases of failure, for example for empty files and directories,
these functions fail to report an error, in the sense that
.Xr ERR_get_error 3
does not work.
.Pp
Even in case of failure, for example when parsing one of the
files or certificates fails,
.Fn SSL_add_file_cert_subjects_to_stack
and
.Fn SSL_add_dir_cert_subjects_to_stack
may still have added some certificates to the stack.
.Pp
The behaviour of
.Fn SSL_add_dir_cert_subjects_to_stack
is non-deterministic.
If parsing one file fails, parsing of the whole directory is aborted.
Files in the directory are not parsed in any specific order.
For example, adding an empty file to
.Fa dir
may or may not cause some of the other files to be ignored.
